Advanced structures with tailored functionality

In the nanowire geometry, the chemical composition can be changed in both the axial and the radial direction, leading to corresponding heterostructures and/or doping profiles. Such design concepts still strongly resemble established planar structures. Beyond those strategies, we investigate more advanced structures with the aim to tailor functionality in entirely new directions. For example, we synthesize nanowire heterostructures that are bent in a pre-defined way and employ the resulting complex strain gradients to influence radiative recombination processes. In addition, in many III-V nanowires both the wurtzite and zincblende crystal structure form. We exploit this polytypism to study crystal phase quantum structures of various dimensionalities with inherently atomically sharp interfaces and free from alloy disorder. In combination with compositional heterostructures, we realize complex topologies like quantum rings. Furthermore, we utilize dielectric confinement to modify radiative recombination in ultrathin nanowires.

We recently concluded the project InterPhase that was funded by the Federal Ministry of Education and Research. This project was devoted to charge and energy transfer processes at hybrid organic/inorganic semiconductor interfaces. Our main contribution to this project was the successful passivation of GaN nanowires with organic molecules resulting in a fivefold increase of the nanowires' radiative efficiency.

Author: P. Corfdir , O. Marquardt , R. B. Lewis , C. Sinito , M. Ramsteiner , A. Trampert , U. Jahn , L. Geelhaar , O. Brandt , V. M. Fomin
Title: Excitonic Aharonov-Bohm oscillations in core-shell nanowires
Source: Adv. Mater. , 31 , 1805645 ( 2019 )
DOI: 10.1002/adma.201805645

Author: R. B. Lewis , P. Corfdir , H. Küpers , T. Flissikowski , O. Brandt , L. Geelhaar
Title: Nanowires bending over backward from strain partitioning in asymmetric core-shell heterostructures
Source: Nano Lett. , 18 , 2343 ( 2018 )
DOI: 10.1021/acs.nanolett.7b05221

Author: P. Corfdir , H. Li , O. Marquardt , G. Gao , M. R. Molas , J. K. Zettler , D. van Treeck , T. Flissikowski , M. Potemski , C. Draxl , A. Trampert , S. Fernández-Garrido , H. T. Grahn , O. Brandt
Title: Crystal-phase quantum wires: One-dimensional heterostructures with atomically flat interfaces
Source: Nano Lett. , 18 , 247 ( 2018 )
DOI: 10.1021/acs.nanolett.7b03997

Author: J. K. Zettler , P. Corfdir , C. Hauswald , E. Luna , U. Jahn , T. Flissikowski , E. Schmidt , C. Ronning , A. Trampert , L. Geelhaar , H. T. Grahn , O. Brandt , S. Fernández-Garrido
Title: Observation of dielectrically confined excitons in ultrathin GaN nanowires up to room temperature
Source: Nano Lett. , 16 , 973 ( 2016 )
DOI: 10.1021/acs.nanolett.5b03931